raspi_gpio_driver

changeset 2:a7543d592206 tip

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- interrupt debouncing (crude) - blinking another led when pressing the button - using broadcom custom pullup/down function
author John Tsiombikas <nuclear@member.fsf.org>
date Sat, 05 Mar 2016 04:55:03 +0000
parents acfcd119e532
children
files gpio.c
diffstat 1 files changed, 20 insertions(+), 3 deletions(-) [+]
line diff
     1.1 --- a/gpio.c	Sat Mar 05 04:25:33 2016 +0000
     1.2 +++ b/gpio.c	Sat Mar 05 04:55:03 2016 +0000
     1.3 @@ -5,8 +5,11 @@
     1.4  #include <linux/interrupt.h>
     1.5  #include <asm/uaccess.h>
     1.6  #include <linux/gpio.h>
     1.7 +#include <linux/jiffies.h>
     1.8 +#include <linux/platform_data/bcm2708.h>
     1.9  
    1.10  #define TEST_OUTPUT_PIN	4
    1.11 +#define TEST_OUTPUT_GREEN	17
    1.12  #define TEST_INPUT_PIN	22
    1.13  
    1.14  static int dev_init(void);
    1.15 @@ -43,12 +46,14 @@
    1.16  	printk("gpio module registered (device: %d)\n", major);
    1.17  
    1.18  	gpio_direction_output(TEST_OUTPUT_PIN, 0);
    1.19 -	gpio_direction_input(TEST_INPUT_PIN);
    1.20 +	gpio_direction_output(TEST_OUTPUT_GREEN, 0);
    1.21  
    1.22  	if(gpio_request(TEST_INPUT_PIN, "test_input") != 0) {
    1.23  		printk("gpio: failed to get input gpio pin\n");
    1.24  		return -1;
    1.25  	}
    1.26 +	gpio_direction_input(TEST_INPUT_PIN);
    1.27 +	bcm2708_gpio_setpull(gpio_to_chip(TEST_INPUT_PIN), TEST_INPUT_PIN, BCM2708_PULL_DOWN);
    1.28  	if((intr_num = gpio_to_irq(TEST_INPUT_PIN)) < 0) {
    1.29  		printk("gpio: failed to get interrupt line for gpio pin\n");
    1.30  		return -1;
    1.31 @@ -65,12 +70,17 @@
    1.32  static void dev_exit(void)
    1.33  {
    1.34  	printk("gpio exit\n");
    1.35 +
    1.36  	unregister_chrdev(major, "gpio");
    1.37  
    1.38  	if(intr_num != -1) {
    1.39  		free_irq(intr_num, "gpio");
    1.40  	}
    1.41  	gpio_free(TEST_INPUT_PIN);
    1.42 +
    1.43 +	gpio_direction_input(TEST_OUTPUT_PIN);
    1.44 +	gpio_direction_input(TEST_OUTPUT_GREEN);
    1.45 +	bcm2708_gpio_setpull(gpio_to_chip(TEST_INPUT_PIN), TEST_INPUT_PIN, BCM2708_PULL_OFF);
    1.46  }
    1.47  
    1.48  static int dev_open(struct inode *inode, struct file *file)
    1.49 @@ -89,8 +99,6 @@
    1.50  {
    1.51  	unsigned char val;
    1.52  
    1.53 -	printk("dev_write(%d) called\n", sz);
    1.54 -
    1.55  	if(sz < 1) {
    1.56  		return 0;
    1.57  	}
    1.58 @@ -104,6 +112,15 @@
    1.59  
    1.60  static irqreturn_t intr_handler(int inum, void *devid, struct pt_regs *regs)
    1.61  {
    1.62 +	static unsigned long ignore_until;
    1.63 +	unsigned long now = jiffies;
    1.64 +
    1.65 +	if(time_before(now, ignore_until)) {
    1.66 +		return IRQ_HANDLED;
    1.67 +	}
    1.68 +	ignore_until = now + 128 * HZ / 1000;
    1.69 +
    1.70  	printk("presses: %d\n", num_presses++);
    1.71 +	gpio_set_value(TEST_OUTPUT_GREEN, num_presses & 1);
    1.72  	return IRQ_HANDLED;
    1.73  }